aperture

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Apertural lip wide and flaring, but hardly incrassate.
Apertural lip holotype expanded and flaring, slightly reflected and somewhat incrassate.
It differs not only considerably in size, but also in the rather different arrangement of apertural barriers and in sculpture of both the protoconch and teleoconch, which characters also separate it from all other Avakubia species.
Diagnosis: Shell lenticular, periphery rounded; aperture strongly descendant; umbilical width moderate; whitish to fawn, characteristically patterned with 3 or 4 dark brown spiral bands, 1 or 2 above periphery, 2 below; sculpture of close-set, incised spiral striae; apertural rim reflected.
This difference between overlapping and non-overlapping apertural lophae appears to be real and not an effect of acetolysis, since the apertures in the overlapping type are often more, rather than less, broad than the non-overlapping.
This implies that the apertural wedge strategy is not necessary for barnacle predation by N.
salpinx, it is clear that allowance must be made for some individual variation in size at maturity, L/D ratio, spiral cord number and strength of apertural dentition.
Southeast African specimens develop mature apertural features at a smaller size than those from the north-western Indian Ocean and Red Sea, and never attain such a large size (largest southern African specimen, length 9.
Recently a number of similar specimens has been collected in the northern Drakensberg escarpment (see above) exhibiting considerable variation in size, shape, sculpture and apertural dentition.
In terms of shell features, Capitina is characterised by the brown spiral lines on the adapical surface, wrinkled sculpture and thickened apertural lip of the adult.